Our long-term goal is to develop a clinical instrument, the 2-photon ophthalmoscope, for non-invasive, high-resolution and repetitive imaging of biochemical processes within the human retina. Such an instrument will have tremendous potential for early detection of age and disease related changes in the eye, long before pathological manifestations of retinal disease become obvious. This real-time retinal imaging instrument will also be critical for rapid evaluation of various pharmacological agents used to treat retinal pathologies. The method has the great advantage of imaging endogenous retinoid fluorophores in their native state without the need for additional staining. In Phase I, we seek to answer whether two-photon excitation based imaging can track age related changes in the retina and then whether a 2-photon ophthalmoscope, with the ultimate goal of clinical instrument can be made. We are proposing three specific aims: (1) Determine whether two-photon excitation imaging can be used to monitor age related changes in human retina;(2) Image the eye of a living monkey to determine the feasibility of two-photon adaptive optics ophthalmoscope system for non-invasive, in vivo imaging of human retinal pigment epithelium cells;and (3) Determine if the size and cost of the instrument could be reduced by replacing the Ti:Sapphire modelocked laser with a femtosecond fiber laser to validate commercialization plans. Once these aims are fulfilled, in Phase 2 we will use the derived data to adapt the two-photon adaptive optics ophthalmoscope for imaging human eyes in vivo and characterize two-photon fluorescence in eyes affected by retina diseases. In addition, the use of the fiber laser and micro-electro- mechanical systems deformable mirror technology, in adaptive optics design, promises to reduce the cost and allow the physical footprint of the instrument to be kept small, greatly aiding potential commercialization. PUBLIC HEALTH RELEVANCE: We seek to develop a novel instrument for noninvasive imaging of the back of the eye with sub-cellular resolution. The instrument will visualize the age or disease related changes in the biochemical processes within human retina, specifically retinoid cycle. Our goal is to further understanding of the biochemistry of vision to allow for rapid evaluation of various pharmacological interventions to prevent retinal degeneration and other pathologies at the early stages, before the retina degenerates and vision is irreparably damaged.